While acknowledging there was problems with getting the script right, Disney Studios' chief Alan Horn says everything is on track and they are almost done with the casting.

"Star Wars Episode 7" has hit the set for filming although no new cast was announced. During a recent panel at Loyola Marymount University School of Film and Television in Los Angeles, Disney Studios chairman Alan Horn said, "We're actually shooting some of it now."

Does it mean that the casting is complete? "We have a lot of them [in place]," the exec revealed, before adding, "We're just not completely done yet." He, however, refused to divulge any further, channeling his inner Yoda as saying, "Patience you must have."

Horn admitted getting the script right was a challenge, "It's all about the screenplay. It has to be screenplay, screenplay, screenplay." When asked about the storyline, he said it would pick up "where 6 left off - and where 6 left off is 35 years ago by the time this is released."

An early draft of the screenplay was written by "Toy Story 3" scribe Michael Arndt, before director J.J. Abrams took it over with Lawrence Kasdan. The much-awaited movie is scheduled to make its way out across the States on December 18, 2015.

Dominic Monaghan previously shed some lights on what to expect from the new cast. The former star of Abrams' show "Lost" said the producers were putting together "a cast of unknowns." He explained, "What he said was, 'We don't want to fall into that mistake of people going 'Oh it's that guy from that thing!' and then you're completely out of the 'Star Wars' universe.' "